bucket list

Yike's, cracked piston, now quiet engine

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Anyone know what brand of piston this 94mm this is, there is no markings on it.

This engine was running fine, only replaced it because the compression was a little low, leak down test showed about 40% past the rings and of course the engine was noisy even though the piston skirt to cyl. clearance was well within spec. I was hoping a new piston would quiet it down a little, bit the new Cylinder Works BB kit quieted it down a lot!

I can only imagine if i rode this thing HARD with that cracked piston, that it would exploded at some point.

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And for those that are so against lapping in valves, my lapping in of 2 Wiesco ex. valves and 2 old stock in. valves have lasted 25,000 kms with no leakage and no tightening.

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Are you installing a CW or it had CW kit? CW uses Vertex pistons which come in 4 different sizes. A-D and the difference is .01mm. The size is on the top of the piston if it is a Vertex.


No it's not a Vertex, i cleaned the carbon off the top of the piston and look what we have. How did this thing not explode?
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Can you tell what brand piston from the numbers on the top?
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No it's not a Vertex, i cleaned the carbon off the top of the piston and look what we have. How did this thing not explode?
20180416_143533.jpg.63dc407aa17477457c1979c6f578a68d.jpg20180416_143345.jpg.8265f23104fe882b22c186f34ed5e2e4.jpg
Can you tell what brand piston from the numbers on the top?
I did some Google searching and that is the old Cylinder Works piston. I found a post on here that said it was a Wiseco piston. I would call Cylinder Works and ask.
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Looks like a wiseco.  Forged pistons are tough but even they have a finite life.

If it makes you feel better I am certain that a cast piston put through the exact same service as this one would have come apart already.

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Good find Ohio well hope the Vertex quality is better with the new CW kit i put in, i'm going off into some very remote places.
A little concerned with the new cylinder surface, looks to me like an aluminium spot showing through the nickicil liner.
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whoa, you dodged the bullet on that one .. on the bore i personally would let it eat, that wont destroy your motor if it does decide to go bad, just rejug it if it does ..

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Posted (edited)

That part number matches the piston in this kit, which is identified in the description as a Vertex:

https://www.denniskirk.com/cometic/big-bore-complete-cylinder-kit-41001-k01.p140420.prd/140420.sku

That bullet you dodged parted your hair Randy. Chit, that could have been a locked wheel at speed. The question is what happened to that piston and how can this be prevented?

Edited by shuswap1
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Posted (edited)

1 hour ago, bucket list said:


 

 


Good find Ohioemoji106.png well hope the Vertex quality is better with the new CW kit i put in, i'm going off into some very remote places.
A little concerned with the new cylinder surface, looks to me like an aluminium spot showing through the nickicil liner. emoji54.png
20180414_114529.jpg20180414_114542.jpg

 

I would run that all day. I’m no expert however, but I would run that all day lol.

Edited by g steezy
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6 hours ago, bucket list said:

I can only imagine if i rode this thing HARD with that cracked piston, that it would exploded at some point.emoji32.png

 

If you never rode it hard, what cracked the piston?

What fuel do you run?

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His videos show the old fella riding sedately, maybe the engine wasn't able to get up to temp?:lame:

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His videos show the old fella riding sedately, maybe the engine wasn't able to get up to temp?:lame:
Haha, ya it's true my racing days are long over and i just like to go exploring up in the mountains now. I have run it for hours at a time at 120 kph on the hiway, i do run 91 to 93 octane non ethanol fuel always, but the key i think is TIME. I've got 450 hours on it and the previous owner had just as much on it, so 900+ hours, 50,000 kms is probably near the limit you could ever expect for a piston in these engines.
As far as that aluminum looking mark on the new cylinder, i'm going to use modern technology and inspect the insides with a bore scope after running it hard on a breakin and before i take it out into the wilderness.

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Have you spoken to the shop about that bore?

I would, I would want it understood and in writing that if it fails within a certain time, or the mark looks worse or measures larger when inspected, that they will replace it. If not then it gets rejected and goes back to them.

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9 hours ago, bucket list said:


 

 


No it's not a Vertex, i cleaned the carbon off the top of the piston and look what we have. emoji33.png How did this thing not explode?
20180416_143533.jpg20180416_143345.jpg
Can you tell what brand piston from the numbers on the top?

 

looks like it touched the valves

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6 hours ago, DrzDick said:

Have you spoken to the shop about that bore?

I would, I would want it understood and in writing that if it fails within a certain time, or the mark looks worse or measures larger when inspected, that they will replace it. If not then it gets rejected and goes back to them.

I am the shop that did the work, but I am going to send the pictures to Cylinder Works and see what they say.

Also pictures of that cracked piston cuz it does have a CW part # on it. Just the piston in the new kit has totally diffrent marking and numbers on it, hopefully an up grade.

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4 hours ago, ohgood said:

looks like it touched the valves

No didn't touch valves, no marks and I floated that combustion chamber, there's no leakage past the valves at all.

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That's a calibrated blow by release designed to extend the life of the piston rings and cylinder wall.  Looks like it did its job and you caught it just in time for maintenance.    Lucky you!

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1 hour ago, bucket list said:

I am the shop that did the work, but I am going to send the pictures to Cylinder Works and see what they say.

Also pictures of that cracked piston cuz it does have a CW part # on it. Just the piston in the new kit has totally diffrent marking and numbers on it, hopefully an up grade.

900 as in NINE HUNDRED hours :lol: Ya Id say you got your moneys worth out of it.. Though I still would not expect a fracture like that unless there was pre ignition, hydro locked at some point, or contact with the head. In the first pic there is what looks like might be what is sometimes called the "Ring of death" that clean ring around the edge of the piston which happens when you have a worn out rod bearing ....if the pic is deceiving, then no worry's.. but if there is a clean ring on the outer edge of the piston Id be checking the rod for wear
On that spot in the new cylinder.... Id have done what you did, send notice to CW, let them decide it needs looked at or run it. The cross hatching looks even and normal on both sides and the spot, if it was failed nikasil plating I would guess the cross hatching would look different between the soft aluminum and ultra hard nikasil plating..
Make sure you get written response from CW if they say run it, not just the phone call. If later inspection shows nikasil plating flaking off on that spot, you do not want to have to reply on a phone conversation. 

CW has been awesome in customer service for me, no complaints. They once a year ago or so replaced a likely damage din shipping crank shaft no questions, even though it was shipped by a third party in a box stuffed lightly with newspaper to "save money"  vice over packing the original box and packing material. 

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